Messages in this thread | | | Subject | Re: [PATCH] ipc/sem: ensure we left shift a ULL rather than a 32 bit integer | From | Colin Ian King <> | Date | Fri, 28 Oct 2016 20:29:03 +0100 |
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On 28/10/16 20:21, Manfred Spraul wrote: > Hi Colin, > > On 10/28/2016 08:11 PM, Colin King wrote: >> From: Colin Ian King <colin.king@canonical.com> >> >> The left shift amount is sop->sem_num % 64, which is up to 63, so >> ensure we are shifting a ULL rather than a 32 bit value. > Good catch, thanks. >> CoverityScan CID#1372862 "Bad bit shift operation" >> >> Fixes: 7c24530cb4e3c0ae ("ipc/sem: optimize perform_atomic_semop()") >> Signed-off-by: Colin Ian King <colin.king@canonical.com> >> --- >> ipc/sem.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/ipc/sem.c b/ipc/sem.c >> index ebd18a7..ca4aa23 100644 >> --- a/ipc/sem.c >> +++ b/ipc/sem.c >> @@ -1839,7 +1839,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct >> sembuf __user *, tsops, >> max = 0; >> for (sop = sops; sop < sops + nsops; sop++) { >> - unsigned long mask = 1 << ((sop->sem_num) % BITS_PER_LONG); >> + unsigned long mask = 1ULL << ((sop->sem_num) % BITS_PER_LONG); >> > Why 1ULL? Is 1UL not sufficient?
For example, 1UL i386 is 32 bits, where as 1ULL is 64. > > -- > Manfred
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